let shim = {};

shim.isNode = () => {
	if (typeof process === 'undefined') return false;
	if (shim.isElectron()) return true;
	return process.title == 'node';
};

shim.isReactNative = () => {
	if (typeof navigator === 'object' && typeof navigator.userAgent === 'string' && navigator.userAgent.indexOf('ReactNativeDebugger') >= 0) {
		return true;
	}
	
	return !shim.isNode();
};

shim.isLinux = () => {
	return process && process.platform === 'linux';
}

shim.isFreeBSD = () => {
	return process && process.platform === 'freebsd';
}

shim.isWindows = () => {
	return process && process.platform === 'win32';
}

shim.isMac = () => {
	return process && process.platform === 'darwin';
}

shim.platformName = function() {
	if (shim.isReactNative()) return 'mobile';
	if (shim.isMac()) return 'darwin'; 
	if (shim.isWindows()) return 'win32'; 
	if (shim.isLinux()) return 'linux';
 	if (shim.isFreeBSD()) return 'freebsd';
	throw new Error('Cannot determine platform');
}

// https://github.com/cheton/is-electron
shim.isElectron = () => {
	// Renderer process
	if (typeof window !== 'undefined' && typeof window.process === 'object' && window.process.type === 'renderer') {
		return true;
	}

	// Main process
	if (typeof process !== 'undefined' && typeof process.versions === 'object' && !!process.versions.electron) {
		return true;
	}

	// Detect the user agent when the `nodeIntegration` option is set to true
	if (typeof navigator === 'object' && typeof navigator.userAgent === 'string' && navigator.userAgent.indexOf('Electron') >= 0) {
		return true;
	}

	return false;
}

shim.isPortable = function() {
	return typeof process !== 'undefined' && typeof process.env === 'object' && !!process.env.PORTABLE_EXECUTABLE_DIR;
}

// Node requests can go wrong is so many different ways and with so
// many different error messages... This handler inspects the error
// and decides whether the request can safely be repeated or not.
shim.fetchRequestCanBeRetried = function(error) {
	if (!error) return false;

	// Unfortunately the error 'Network request failed' doesn't have a type
	// or error code, so hopefully that message won't change and is not localized
	if (error.message == 'Network request failed') return true;

	// request to https://public-ch3302....1fab24cb1bd5f.md failed, reason: socket hang up"
	if (error.code == 'ECONNRESET') return true;

	// OneDrive (or Node?) sometimes sends back a "not found" error for resources
	// that definitely exist and in this case repeating the request works.
	// Error is:
	// request to https://graph.microsoft.com/v1.0/drive/special/approot failed, reason: getaddrinfo ENOTFOUND graph.microsoft.com graph.microsoft.com:443      
	if (error.code == 'ENOTFOUND') return true;

	// network timeout at: https://public-ch3302...859f9b0e3ab.md
	if (error.message && error.message.indexOf('network timeout') === 0) return true;

	// name: 'FetchError',
	// message: 'request to https://api.ipify.org/?format=json failed, reason: getaddrinfo EAI_AGAIN api.ipify.org:443',
	// type: 'system',
	// errno: 'EAI_AGAIN',
	// code: 'EAI_AGAIN' } } reason: { FetchError: request to https://api.ipify.org/?format=json failed, reason: getaddrinfo EAI_AGAIN api.ipify.org:443
	//
	// It's a Microsoft error: "A temporary failure in name resolution occurred."
	if (error.code == 'EAI_AGAIN') return true;

	// request to https://public-...8fd8bc6bb68e9c4d17a.md failed, reason: connect ETIMEDOUT 204.79.197.213:443
	// Code: ETIMEDOUT
	if (error.code === 'ETIMEDOUT') return true;

	// ECONNREFUSED is generally temporary
	if (error.code === 'ECONNREFUSED') return true;

	return false;
};

shim.fetchWithRetry = async function(fetchFn, options = null) {
	const { time } = require('lib/time-utils.js');

	if (!options) options = {};
	if (!options.timeout) options.timeout = 1000 * 120; // ms
	if (!('maxRetry' in options)) options.maxRetry = 5;

	let retryCount = 0;
	while (true) {
		try {
			const response = await fetchFn();
			return response;
		} catch (error) {
			if (shim.fetchRequestCanBeRetried(error)) {
				retryCount++;
				if (retryCount > options.maxRetry) throw error;
				await time.sleep(retryCount * 3);
			} else {
				throw error;
			}
		}
	}
}

shim.fetch = () => { throw new Error('Not implemented'); }
shim.FormData = typeof FormData !== 'undefined' ? FormData : null;
shim.fsDriver = () => { throw new Error('Not implemented') }
shim.FileApiDriverLocal = null;
shim.readLocalFileBase64 = (path) => { throw new Error('Not implemented'); }
shim.uploadBlob = () => { throw new Error('Not implemented'); }
shim.sjclModule = null;
shim.randomBytes = async (count) => { throw new Error('Not implemented'); }
shim.setInterval = function(fn, interval) {
	return setInterval(fn, interval);
}
shim.clearInterval = function(id) {
	return clearInterval(id);
}
shim.stringByteLength = function(string) { throw new Error('Not implemented'); }
shim.detectAndSetLocale = null;
shim.attachFileToNote = async (note, filePath) => {}
shim.imageFromDataUrl = async function(imageDataUrl, filePath, options = null) { throw new Error('Not implemented') }
shim.Buffer = null;
shim.openUrl = () => { throw new Error('Not implemented'); }
shim.waitForFrame = () => { throw new Error('Not implemented'); }
shim.injectedJs = name => '';
shim.loadCssFromJs = name => { throw new Error('Not implemented'); }

module.exports = { shim };
